Load-handling apparatus with reach mechanism

ABSTRACT

A lift truck with an elevatable carriage mounting, through extensible reach mechanism, load-holding structure, such as lifting forks. The reach mechanism includes a horizontal torque shaft which extends across the support frame, and a pair of laterally spaced extensible folding arm assemblies which join to opposite ends of the torque shaft and extend forwardly to the load-holding structure. The load-holding structure is moved between extended and retracted positions with respect to the carriage by operation of a double-acting ram operatively connected to the reach mechanism. A line which supplies pressure fluid to the ram to actuate it in a contraction stroke to produce contraction of the reach mechanism includes a pilot-operated check valve operable to maintain a pressurized condition in such line upon stopping of the contraction stroke in the ram. Near completion of the contraction stroke, stop means on the support frame engages the load-holding structure. The stop means and the check valve act firmly to hold the load-holding structure in its retracted position.

United States Patent Baughman [54] LOAD-HANDLING APPARATUS WITH REACH MECHANISM Gaylord G. Baughman, Troutdale, Oreg.

[73] Assignee: Cascade Corporation, Portland, Oreg.

[22] Filed: April 6, 1970 [21] Appl. No.1 25,802

[72] Inventor:

[ 51 July 11,1972

Primary Examiner-Robert G. Sheridan Assistant Examiner-Lawrence J. Oresky Attorney-Kolisch & Hartwell [57] ABSTRACT A lift truck with an elevatable carriage mounting, through extensible reach mechanism, load-holding structure, such as lifting forks. The reach mechanism includes a horizontal torque shaft which extends across the support frame, and a pair of laterally spaced extensible folding arm assemblies which join to opposite ends of the torque shaft and extend forwardly to the load-holding structure. The load-holding structure is moved between extended and retracted positions with respect to the carriage by operation of a double-acting ram operatively connected to the reach mechanism. A line which supplies pressure fluid to the ram to actuate it in a contraction stroke to produce contraction of the reach mechanism includes a pilot-operated check valve operable to maintain a pressurized condition in such line upon stopping of the contraction stroke in the ram. Near completion of the contraction stroke, stop means on the support frame engages the load-holding structure. The stop means and the check valve act firmly to hold the load-holding structure in its retracted position.

2 Claims, 8 Drawing Figures PKTENTEDJUL 1 I 1972 sum-:1 1 or 2 GAYLORD G.

BAUGH MAN INVENTOR.

LOAD-HANDLING APPARATUS WITH REACH MECHANISM This invention relates to load-handling apparatus, and more particularly to such apparatus which features load-holding structure mounted, through extensible reach mechanism, on a support frame.

As exemplified by the preferred embodiment of the invention herein disclosed, such load-handling apparatus may take the form of an attachment for a lift truck, where reach mechanism is included to permit the load-holding structure to be extended out from the vehicle to pick up and deposit loads at locations that otherwise would be inaccessible.

For reasons of safety, increased maneuverability, and to ob tain optimum load distribution while transporting a load, the reach mechanism is contracted to bring the load-holding structure adjacent the usual mast assembly in the lift truck when the lift truck is traveling from one location to another. With such a condition existing, it is important that the loadholding structure be held positively in its retracted position closely adjacent the mast assembly, since, should the vehicle be decelerated abruptly, the load and its supporting structure, through momentum, would tend to move forwardly from the mast.

A general object of the invention, therefore, is to provide novel load-handling apparatus which includes a support frame, load-holding structure mounted on the support frame through extensible reach mechanism which is operable to move the load-holding structure between an extended position spaced forwardly of the support frame and a retracted position close to the support frame, and releasable restraining means for automatically holding the load-holding structure in its retracted position. The restraining means is operable to prevent forward movement of the load-holding structure from its retracted position on deceleration of the vehicle on which it may be mounted.

In a preferred embodiment of the invention, the reach mechanism is powered for extension and retraction by a fluidoperated motor mounted on the support frame. A source of pressure fluid for actuating the motor is mounted on the vehicle, with flexible conduits for supplying and exhausting pressure fluid from the motor interconnecting the source and the motor. The restraining means is a releasable check valve mounted on the support frame closely adjacent the motor, and interposed between the pressure fluid source and motor in that conduit which supplies pressure fluid to the motor during retraction of the load-holding structure.

Another object is to provide novel extensible reach mechanism for mounting the load-holding structure on the support frame. The reach mechanism includes a pair of horizontally spaced folding arm assemblies, each of which is extensible by reason of arms in the assembly swinging in a vertical plane. Outer extremities of the assemblies connect with opposite sides of the load-holding structure. With the folding arm assemblies so positioned, excellent vertical support is provided for the load-holding structure. I

Still another object is to provide, in conjunction with such folding arm assemblies, a power-driven torque shaft rotatably mounted on the support frame, with the shaft extending between and being secured at its ends to the folding arm assemblies in such a manner that rotation of the shaft in one direction simultaneously extends the arm assemblies to move the load-holding structure forwardly, and rotation of the shaft in the opposite direction simultaneously retracts the arm assemblies.

These and other objects and advantages will become more fully apparent as the following description is read in conjunction with the drawings, wherein:

FIG. 1 is a side elevation view of load-handling apparatus constructed in accordance with an embodiment of the invention, with such attached to a vertically movable carriage on the forward end of a lift truck;

FIG. 2 is an enlarged top view taken generally along the line 22 in FIG. 1;

FIG. 3 is an enlarged side elevation view of the apparatus in a retracted position;

FIG. 4 is a cross-sectional view, taken generally along the line 4-4 in FIG. 3;

FIG. 5 is cross-sectional view, taken generally along the line 5-5 in FIG. 3;

FIG. 6 is a perspective view of a torque shaft which forms a portion of the apparatus;

FIG. 7 is a schematic diagram of a fluid pressure system which is operable to control the actuation of a fluid-operated motor in the invention; and

FIG. 8 is a view of the top side of an arm in the apparatus, with such removed from the apparatus.

Referring now to the drawings, and first more specifically to FIG. 1, at 10 is indicated generally a lift truck having an upright mast 12 mounted on its front end. A carriage 14 is mounted on the mast for vertical movement relative thereto. Mounted on carriage 14 for vertical movement therewith, and indicated generally at 18, is load-handling apparatus according to the invention.

In broad terms, apparatus 18 includes a support frame 22 secured to the carriage, extensible reach mechanism 26 connected at its rear end to frame 22 and extending forwardly therefrom, and loadholding structure 30 connected to the forward end of reach mechanism 26 for movement toward and away from support frame 22. The load handling apparatus is so constructed as to be substantially symmetrical on opposite sides of a vertical plane which extends forwardly of the lift truck along the center line of apparatus 18.

Referring specifically to FIG. 3, support frame 22 includes a pair of parallel, laterally spaced, upright channels 34, 36. Each channel is positioned with its central web adjacent cam'age l4 and its flanges projecting forwardly, or to the right in FIGS.

' 1-3. Channels 34, 36, are joined by an elongated horizontal plate 38 which extends therebetween intermediate the ends of channels 34, 36, and is secured at its ends to the channels, as by welding. An elongated, upright plate 40 also extends between the channels, and is secured, as by welding, adjacent to its opposite ends to the lower portions of channels 34, 36. An upper hook member 42 is secured to the rear side of plate 38. This fits over an upwardly projecting lip on carriage 14. A lower hook member 44 secured to plate 40 fits over a lower lip on the carriage. The hook plates thus secure the support frame to the carriage.

At the top of the support frame, and on either side of the frame, are a pair of posts 48, 50.

Load-holding structure 30 includes a pair of upright, laterally spaced channels 52, 54. Channel 52 for the most part obscures channel 54 in FIG. 3. The channels are positioned with their flanges extending rearwardly, or to the left in FIGS. 1-3, from their central webs. Channels 52, 54 are interconnected by horizontal, vertically spaced, elongated upper and lower hook members 56, 57 which extend across the forward sides of channels 52, 54. Channels 52, 54 also have secured to and projecting upwardly from their tops posts such as that noted at 58 for channel 52, similar to posts 48, 50. A pair of load support forks, such as the one shown at 59, are mounted on hook members 56, 57.

Reach mechanism 26 includes a pair of folding arm assemblies 60, 61 positioned adjacent opposite sides of the apparatus. The assemblies are similar in construction, and thus only one will described in detail.

Considering assembly 60, such comprises a first elongated inclined arm 62, a second elongated inclined arm 70 hinged at 72 to the forward end of am 62, a third elongated inclined arm 76 hinged through a pin 80 to an intermediate portion of arm 62, and a fourth elongated inclined arm 84 hinged at its rear end at to the forward extremity of the third arm and hinged intermediate its ends through a pin 86 to an intermediate portion of second arm 70. The various hinge connections permit relative swinging of the arms in a vertical plane.

Referring to FIGS. 2 and 8, arm 62 is shown as comprising a pair of elongated side portions 62c, 62d which extend along the length of the arm. Joining the two side portions adjacent opposite ends of the arm, and spacing the side portions laterally from each other are webs 62e, 62f. With the construction described, an elongated hollow interior is provided in arm 62, intermediate the ends of the arms where webs 62e, 62f are located. This hollow interior is used to receive arm 76 which extends through arm 62.

Further to be noted is that the left end of arm 62 in FIG. 8 is bifurcated with legs 62a presented. As seen in FIG. 2, these legs straddle post 48 with the arm mounted in place. The right end of the arm in FIG. 8 also is bifurcated with spaced-apart legs 62g presented, these legs being offset slightly from the longitudinal midline of the arm.

Arm 70 in FIG. 1 may have the same construction as that described for arm 62. In mounting the arm in the assembly, the end of arm 70 which has legs corresponding to legs 62g are interfitted with legs 62g in making hinge connection 72. Arm 84 may have a construction similar to arm 76, and such arm passes through the hollow interior region of arm 70.

The construction of arm assembly 60 with various arms that make up the assembly has been discussed in some detail. A similar construction may be utilized in the construction of arm assembly 61 and the various arms in this assembly.

With an arm assembly constructed as described, a relatively compact arrangement results with contraction of the arm as sembly, as is best illustrated in FIG. 3. Further, the construction provides for uniform multiple shear loading of pivot pins such as those shown at 80 and 86. It should be noted also that in the manufacture of both arm assemblies only two basic types of arms need be utilized, since arm 76 may be identical to arm 84, and arm 62 may be identical to arm 70.

Considering the mounting of the rear portion of arm assembly 60 on support frame 22, and referring to FIGS. 2 and 4, a pin 92 extends through the post and has ends lodged within legs 62a. This pin journals the rear end of the arm on the post. A torque shaft, shown at 94 in FIG. 2, terminates at the end which is adjacent arm 62 in an integral cap 96. (For a perspective view of the torque shaft reference is made to FIG. 6.) Cap 96 abuts against the inner side of arm 62. A retainer 98 substantially matching cap 96 abuts against the opposite side of arm 62. The cap and retainer, together with arm 62, are secured together by a nut and bolt assembly 102. This nut and bolt assembly, together with pin 92 which has ends received within recesses provided in the retainer and cap, provide a relatively easily disassembled hinge connection for the rear end of arm 62 on post 48 with the rear end at the same time being joined to torque shaft 94 for rotation with the torque shaft.

Arm 104 in assembly 61 corresponding to arm 62 is mounted in a similar manner on post 50 with such being secured to the opposite end of the torque shaft for rotation with the shaft.

Arm 76 in assembly 60 has its'rear end mounted for vertical movement in support frame 22 by the construction shown in FIGS. 3 and 5. More specifically, a channel member 34 has been described in connection with support frame 22 which forms one side of the support frame. As seen in FIGS. 3 and 5, rollers 110 are journaled on the end of arm 76 by pin 114 and are lodged within the channel member with sides bearing against the web of the channel member. Forwardly projecting flanges 34a, 34b of the channel member include elongated vertical grooves 118 loosely receiving projection 1100 of the rollers. The weight of reach mechanism 26 and any load on load-holding structure 30 tends to force rollers 1 against the web of the channel member. Projections 110a serve to inhibit any inadvertent displacement of the roller out of the position within the channel member. The channels thus act as guide means permitting vertical movement of the rear ends of arm 76.

The connection of arms 62, 104, to the ends of torque shaft 94 has been described. Referring to FIGS. 2 and 6, provided as an integral part of the torque shaft is a lever arm 120 which projects radially to one side of the torque shaft at a point midway between its ends. This lever arm is used in rotating the torque shaft to produce extension of the various arm assemblies.

A power-operated means is included for shifting the lever arm and producing rotation of the torque shaft under power. In the embodiment of the invention disclosed this takes the form of a double-acting fluid-operated ram, or motor, 140 which has its rod, or extensible, end pivotally joined at 141 to the end of lever 120. The opposite, or cylinder end of the ram is pivotally mounted at 142 on a bracket which is an integral part of frame 22.

With the construction described only one ram need be provided for extending the two arm assemblies simultaneously. The force of the ram is distributed equally to the two arm assemblies through the torque shaft. The ram may be disposed where adequate clearance normally exists in the space provided between the opposite sides of the reach mechanism and between the two arm assemblies in such reach mechanism.

The forward end of arm 84 in assembly 60 and the forward end of the corresponding arm in assembly 61 (obscured in FIG. 1), are mounted for vertical movement in load-holding structure 30 through a channel and roller construction similar to that described with the mounting for the rear end of arm 76. Thus, and referring to FIG. 1, channel 52 as previously described has its side flanges projecting rearwardly. Received within the space bounded by these side flanges of channel 52 are a pair of rollers similar to rollers and represented by the roller shown in dotted outline at 144 in FIG. 1.

The forward end of arm 70 in assembly 60 and the forward end of the corresponding arm in assembly 61 are hinged to upstanding posts in load-holding structure 30. The hinge mount ing of the forward ends of arm 62, 104 with a torque shaft (not shown) being provided similar to torque shaft 94 interconnecting the forward extremities of these arms. By providing torque shafts at the forward extremities of these arms and at the rear extremities of arms 62, 104 and with extension of ram 140, the reach mechanism extends evenly and smoothly with extension of the ram even though an obstruction may be encountered by a part of the load-holding structure which would otherwise cause skewing of the parts.

As illustrated in FIGS. 1, 2, and 3, forwardly extending stops, or abutments, 146 are joined, as by welding, to forwardly projecting flanges of channel members 34, 36 of support frame 22. On the reach mechanism being contracted, rearwardly facing flanges in the channels of load-holding structure 30 come against the ends of these stops, or abutments. Thus the stops define the contracted position of the reach mechanism. The load-holding structure contacts the stops slightly before ram reaches the end of its contrac-,

tion stroke, which is the stroke producing contraction of the reach mechanism.

Referring now to FIG. 7, ram 140 is operatively connected, through a conduit system indicated generally at 148, to a source of fluid under pressure 150 mounted on the vehicle. The fluid pressure source includes a reservoir 152 and a pump 154. A supply conduit 158 connects pump 154 to a control valve 160 and a return line 162 connects the control valve 160 directly to the reservoir. A dash-dot outline 163 surrounds ram 140 and that portion of the conduit system which is mounted on the support frame, and a dash-dot outline 165 surrounds that portion of the conduit system which is on the vehicle.

A pair of elongated, flexible conduits 164, 166 are connected at one set of their ends to control valve 160. The control valve is shiftable between three positions. With the control valve in the position illustrated in FIG. 7, fluid under pressure supplied by pump 154 to conduit 158 is returned directly through conduit 162 to the reservoir. With the control valve shifted to the left in FIG. 7, conduit 158 is connected to conduit 164 and conduit 162 is connected to conduit 166. With the control valve shifted to the right in FIG. 7, conduit 158 is connected to conduit 166 and conduit 162 is connected to conduit 164. v

A pilot-operated check valve 170, as seen in FIGS. 2 and 3, is mounted on plate 38 of support frame 22. Referring again to FIG. 7, check valve 170 includes a first chamber 172 in which is mounted a spring-biased ball 174. Chamber 172 is connected through a bore 176 with another chamber 178. Ball 174 is biased to the right in FIG. 7 and serves to close off the left end of bore 176. A piston 180, having a rod 182 secured to its left end, is mounted for reciprocal movement in chamber 178. Rod 182 extends through bore 176 and is moved toward and away from ball 174 on movement of the piston.

Conduit 164 is connected to the right end of chamber 178, as seen in FIG. 7, and conduit 166 is connected to an intermediate region of bore 176. It should be understood that conduits 164, 166 have sufficient length and flexibility to accommodate vertical movement of the check valve with the support frame and carriage.

A conduit 186 connects chamber 172 with the upper end of the ram 140 and a conduit 190 connects the lower end of the ram with conduit 164, as seen in FIGS. 2 and 7. Conduits 186, 190 are relatively short in comparison to conduits 164, 166.

With control valve 160 shifted to the right, fluid under pressure will be supplied to conduit 166 to force ball 174 away from bore 176 and permit fluid to pass from conduit 166, through conduit 186, to the upper end of ram 140 to contract the ram. Fluid from the lower end of the ram exhausts to reservoir 152 through conduits 190, 164 and 162.

With the control valve shifted to the left, fluid under pressure is supplied through conduit 190 to the lower end of ram 140 urging the ram to extend and to discharge fluid from its upper end through conduit 186. Fluid initially is prevented from discharging through conduit 186 by ball 174 in the check valve. Fluid under pressure supplied to conduit 190 also is supplied through conduit 164 to chamber 178 and against the right side of piston 180. This pressurized fluid acting against the right side of piston 180 forces it to move to the left with piston rod 182 forcing ball 174 away from bore 176. This permits fluid to discharge from the upper end of the ram and the ram to extend.

With the control valve in the position shown in FIG. 7, pressurized fluid is supplied to neither end of ram 140 and the ram is hydraulically locked against extension by ball 174 in the check valve maintaining a pressurized condition in line 186.

Explaining now the operation of the apparatus, and with the reach mechanism and load-holding structure in an extended position as illustrated in FIGS. 1 and 2, to retract the badholding structure toward the support frame control valve 160 is shifted to the right in FIG. 7. Fluid under pressure thus is supplied to the upper end of ram 140 to contract it. Contraction of the ram swings lever arm 120 downwardly in FIG. 1 rotating torque shaft 94 in a clockwise direction which serves to collapse folding arm assemblies 60, 61 and retract loadholding structure 30. Structure 30 may be retracted toward the support frame and mast until channel members in the structure engage stops 146.

With load-holding structure 30 in its retracted position, as shown in FIG. 3, it is prevented from being moved rearwardly, toward support frame 22, by stop members 146 and is prevented from being moved outwardly and away from the support frame by the hydraulic locking action provided by check valve 170.

Since check valve 170 is mounted on the support frame closely adjacent ram 140, conduit 186 may be relatively short. Although conduit 186 is flexible, any force attempting to extend ram 140 will produce little, if any, expansion in this conduit. Thus, the load-holding structure is restrained from perceptible forward movement. Were check valve 170 to be mounted on the vehicle, a much greater distance from the ram, the additional length of flexible conduit required between the check valve and the upper end of the ram would provide more room for expansion in the conduits, and thus the ram could extend somewhat with structure 30 moving forwardly of the support frame an appreciable distance.

To extend arm assemblies 60, 61, and move load-holding structure 30 forwardly of support frame 22, control valve is shifted to the left in FIG. 7 to extend ram 140. Extension of the ram swin s lever 120, upwardly, as seen in FIG. 1, producing counterc ockwise rotation of torque shaft 94. This rotation of the torque shaft, through its connections with arm assemblies 60, 61, acts to extend the arm assemblies simultaneously to move load-holding structure 30 forwardly.

While an embodiment of the invention has been described herein, it should be obvious to those skilled in the art that variations and modifications are possible without departing from the spirit of the invention.

It is claimed and desired to secure by Letters Patent:

1. In load-handling apparatus including load-holding structure in the form of a platform for supporting the underside of a load, and a support frame mounted for forward progress over the ground,

reach mechanism mounting said load-holding structure on said support frame with such on the forward side thereof, said reach mechanism being extensible to move the loadholding structure from a retracted position where the structure is adjacent the support frame forwardly from said frame toward an extended position where the structure is spaced forwardly from said frame,

fluid-operated motor means operatively interposed between the load-holding structure and support frame actuatable to produce such forward movement of the load-holding structure and also to return the load-holding structure to its retracted position,

a source of fluid under pressure, and

a conduit system connecting said source and said motor means permitting fluid under pressure to be delivered to said motor means to actuate the motor means, said conduit system including control valve means operable to control motor actuation through control of fluid under pressure delivered to the motor means, a line extending between the control valve means and motor means containing fluid under pressure when the motor means is actuated to retract the load-holding structure, another line extending between the control valve means and motor means containing fluid under pressure when the motor means is actuated to extend the load-holding structure, and a pilot-operated check valve in the first-mentioned line operable to maintain a pressurized condition in such line where the line extends from the check valve to the motor means and having a pilot connection with said other line.

2. The apparatus of claim 1, wherein the motor means comprises a double-acting ram having extension and contraction strokes, with one stroke producing movement of the loadholding structure to its extended position and the other stroke producing movement of the load-holding structure to its retracted position, and said first-mentioned line joins with the end of said ram to which fluid under pressure is supplied to produce said other stroke in the ram, and which further comprises stop means on the support frame which engages the load-holding structure on the latter moving to its retracted position, to inhibit movement of the load-holding structure further toward said support frame, said stop means engaging the load-holding structure prior to said ram completing its said other stroke. 

1. In load-handling apparatus including load-holding structure in the form of a platform for supporting the underside of a load, and a support frame mounted for forward progress over the ground, reach mechanism mounting said load-holding structure on said support frame with such on the forward side thereof, said reach mechanism being extensible to move the load-holding structure from a retracted position where the structure is adjacent the support frame forwardly from said frame toward an extended position where the structure is spaced forwardly from said frame, fluid-operated motor means operatively interposed between the load-holding structure and support frame actuatable to produce such forward movement of the load-holding structure and also to return the load-holding structure to its retracted position, a source of fluid under pressure, and a conduit system conNecting said source and said motor means permitting fluid under pressure to be delivered to said motor means to actuate the motor means, said conduit system including control valve means operable to control motor actuation through control of fluid under pressure delivered to the motor means, a line extending between the control valve means and motor means containing fluid under pressure when the motor means is actuated to retract the load-holding structure, another line extending between the control valve means and motor means containing fluid under pressure when the motor means is actuated to extend the load-holding structure, and a pilotoperated check valve in the first-mentioned line operable to maintain a pressurized condition in such line where the line extends from the check valve to the motor means and having a pilot connection with said other line.
 2. The apparatus of claim 1, wherein the motor means comprises a double-acting ram having extension and contraction strokes, with one stroke producing movement of the load-holding structure to its extended position and the other stroke producing movement of the load-holding structure to its retracted position, and said first-mentioned line joins with the end of said ram to which fluid under pressure is supplied to produce said other stroke in the ram, and which further comprises stop means on the support frame which engages the load-holding structure on the latter moving to its retracted position, to inhibit movement of the load-holding structure further toward said support frame, said stop means engaging the load-holding structure prior to said ram completing its said other stroke. 